Harman Kardon CD491 - Page 16

= CASSETTE MECHANISM ADJUSTMENT AND CONFIRMATION
1. Pinch roller contact timing
1) Run the capstans by placing the POWER switch
in the ON position.
2) Lift the head base slowly until the take-up pinch
roller starts rotating. Then confirm that there is a
clearance of 0.05~ 0.5mm between the supply
pinch roller and the capstan.
Capstan
Clearance
fy 0.05 ~0.5 mm
5 LI} Ae
@ 6 & OO
Supply pinch roller
Not rotating
Take-up pinch roller
Rotating
Fig. 1
3) If the pinch roller contact timing is simultaneous
or reverse, advance the pinch roller contact timing
of the take-up pinch roller by bending the A
section in the below Fig. 2 in the arrow direction
or replace the supply pinch roller assembly.
Note: {f the contact timing has been adjusted by
bending the A section of the head base, be
sure to confirm after the adjustment that
the capstan and the take-up pinch roller are
not in contact while the deck is in the
PAUSE mode.
Head base
Fig, 2
2. Pinch roller parallelism confirmation
1) Push up the head base until right before the
capstan and pinch roller contact and visually
confirm for parallelism of each capstan and the
pinch roller.
Capstan
Parallelism
Pinch roller Fig. 3
2) If out of parallelism, check the pinch arm spindle
for bend and if not bent, replace the pinch roller
assembly.
3. Specification confirmation
Check for the following specifications.
1) Back tension 6 gem (4.5 ~ 8gcm)
2) Pinch roller pressure Tape-up 360g + 40g
Supply 260g + 40g
4. Head height adjustment
1) Install the M-300 head gauge plate.
2) With the unit in the PLAY state, apply the
adjustment chip to the head gauge plate and make
an adjustment with the adjusting screws A and B
in the below Fig. 4 so that the chip doesn’t
contact the tape guide.
‘M-300
Head gauge
plate
Adjustment chip
Tape guide
Adjustment
B Fig. 4
5. Head penetration adjustment
1) Install the M-300 head gauge plate.
2) Apply the adjustment chip to the head and check
for the chip to head clearance. If there is a
clearance, make an adjustment with the adjusting
screw C so that no clearance remains.
Note: 1. There should be no clearance at either
record or playback head.
2, If there is a clearance at either record or
playback head, adjust so that the
clearance will be at the lower side as
shown in the Fig. 5.
3. After the flapping adjustment, re-check
the head height.
M-300
Head gauge plate
Head Adjustment
chip
WiLL
‘Head gauge
Clearance _plate
c Fig. 5
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